1. Field of the Invention
The present invention relates to a bending device and a bending method in which when a pipe, a bar material or another longitudinal work is bent/worked, two bending mechanisms are moved to successively bend the work from its opposite ends toward its center.
2. Description of the Related Art
As disclosed in Japanese Patent Publication No. 13011/1993, a known conventional bending device is provided with a chuck mechanism for holding a pipe or a longitudinal work substantially by its center, two moving mechanisms which can move toward the center position along two tracks provided parallel on opposite sides of the work held by the chuck mechanism, and joint type robots mounted on the moving mechanisms and each having joints rotating around axes parallel with an axial direction of the work. In the bending device, attached to a tip end of each joint type robot is a bending mechanism in which the work is held by a bending die conformed to a bending shape of the work and a clamping die rotating around the bending die, and the work is bent by rotating the clamping die.
The bending process is performed by successively bending the work from its opposite ends toward its center while moving the joint type robots along the work.
In the conventional method, however, when the bending of one place is completed and the joint type robots are moved along the work, the bending mechanism is detached from the work before moving to the next bending position. After the movement, each joint of the joint type robot is rotated to move the bending mechanism in such manner that the work is placed between the bending die and the clamping die of the bending mechanism, which causes a problem that the time necessary for working is lengthened.
Another problem is as follows:
When the work is bent in accordance with design data, in most cases, the work cannot be bent as designed because of difference in hardness and elongation of the work. To solve the problem, after trial working is performed, the differences from the design data are measured, the design data is corrected, and the work is again bent in accordance with the corrected design data. In most cases, the coordinate data of an imaginary point is given as the design. For example, given as the design data are bending points as intersection points which are obtained by extending the center lines of the adjacent straight portions of the work.
Since the bending points are imaginary, the bending points of the bent work cannot directly be measured. Therefore, after the distance between bending portions and the bending angle are measured in the bent work, the bending points are calculated from the measurement data. Moreover, since there are a large number of bending points, it cannot be easily known which bending point is to be corrected when the design data differs from the measurement data. Specifically, if the data of one bending point is corrected, the correction has an influence on the other bending points, which causes a problem that the correcting operation is difficult.
The convention bending device is further provided with an unloading device for detaching the bent work form the chuck mechanism for delivery after the bending process is completed. Since the work is delivered by the unloading device, the device is disadvantageously enlarged in size because a space for installing the unloading device is necessary.